Method of fabricating a heat exchanger



May 12. 1970 E. P. oDDY 3,510,930

METHOD OF FABRICATING A HEAT EXCHANGER original Filed oct. '24, 1965 3 sheets-sheet 1 0 J'nverz'o-'f Zdwczrdfd y E. P. oDDY I 3,510,930

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METHOD OF FABRICATING A HEAT EXCHANGER original Filed oct. 24, 196s 3 sheets-sheet s United States Patent O 3,510,930 METHOD F F ABRI'CATING A HEAT EXCHANGER Edward P. Oddy, Detroit, Mich., assignor to Borg- Warner Corporation, Chicago, Ill., a corporation of Illinois Original application Oct. 24, 1965, Ser. No. 504,915, no7 Patent No. 3,437,134, dated Apr. 8, 1969. Divided and this application June 14, 1968, Ser. No. 796,242 Int. Cl. B21d 53/02; B23p 15/26 U.S. Cl. 29-157.3 4 Claims ABSTRACT OF THE DISCLOSURE The present invention is a divisional application of Ser. No. 504,915 filed Oct. 24, 1965, now Pat` No. 3,437,- 134 and entitled Heat Exhanger and Method of Making Same.

This invention relates to heat exchangers and more particularly to a self-spacing type of fin used therein which lends itself to rapid hand assembly or automatic assembly prior to automatic insertion of the liquid carrying tubes and to a method and apparatus for manufacturing the iin.

Self-spacing fins have heretofore been devised for use in cores for vehicle cooling radiators and other heat exchangers. These cores are formed by stacking fins uniformly spaced from each other and inserting a plurality or coolant tubes through previously formed apertures in the fins. The tube ends interconnect a supply header and a receiving header. It is known that some manufacturers of radiators presently use self-spacing tins. However, those devised in the past and those used at present have certain shortcomings which make it questionable whether the gains obtained by automatic or rapid assembly offset the losses.

Some self-spacer means for fins required the fins to be made of thicker material in order to provide strength to resist distortion by the frictional force of the tubes being pushed through the holes in the fins. This resulted in increased weight and cost of the heat exchanger. By making the holes larger, thinner material could again be used Ibut the larger holes caused loss of contact between the tubes and the tins and subsequently lowered performance. The shape of some spacer means was such that prior to stacking the loose fins would become interlocked requiring separation by hand and thus increasing labor cost. Other spacer means have provided the necessary stiffness and strength for stacking purposes but were of such shape as to cause too much interference with air flow through the core with a resultant loss in performance.

The present invention overcomes all of the aforesaid shortcomings and provides a iin that is easy to manufacture and stack either by hand or automatically with the end result being a heat exchanger of better performance at less cost.

A primary object of the invention is to provide a heat exchanger of the fin and tube type in which struck-out lugs or spacer elements of a unique shape are provided between adjacent tube openings which tend to minimize damage to the ns as the tubes are inserted.

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Another object of the invention is to provide a heat exchanger of the stated type wherein struck-out flow deflectors of similar unique shape are formed in the fin which, together with the spacers, minimize laminar flow of the secondary heat exchange media across the fin element.

Another object of the invention is to provide a heat exchanger structure in which the spacers or the flow deflectors are disposed at an angle to the leading edge of the fin so as to enhance heat dissipation.

Another object of the invention is to provide a heat exchange fin in which the spacers or the flow deectors provide additional secondary heat exchanger areas.

A further object of the invention is to devise a method for making heat exchanger cores in accordance with the present invention.

Another object of the invention is to provide tooling for making a fin element complete with spacers and ow deflectors with a single stamping operation.

Other and more particular objects of the invention will be apparent from the following detailed description and the appended drawings, wherein:

FIG. 1 is an elevational View of a heat exchanger constructed in accordance with the principles of the present invention;

FIG. 2 is a plan view of a portion of a heat exchange fin used in the heat exchanger illustrated in FIG. 1.

FIG. 3 is a greatly enlarged sectional view taken substantially on line 3 3 of 'FIGURE 2;

FIG. 4 is an elevational sectional view taken substantially on line 4-4 of FIG. 2;

FIG. 5 is a plan view of a n made in accordance with a modified form of the present invention;

FIG. 5a is a greatly enlarged elevational view of a spacing unit of the fin illustrated in FIG. 5;

FIG. 6 is a fragmentary plan view of another modified form of the present invention;

FIG, 7 is a fragmentary plan view of another modied form of the present invention;

FIG. 8 is a fragmentary plan view of a still further modified form of the present invention;

FIG. 9 is a greatly enlarged elevational view of a punch used in forming the flow deflectors of FIGS. 2, 3 and 4 and the spacing units of FIG. 7;

FIG. 10 is an elevational view illustrating a punch utilized in forming the spacers and simultaneously forming associated flow deflectors shown in FIGS. 2, 3 and 4;

FIG. 11 is an elevational View illustrating a punch utilized in forming the spacers of FIG. 8; and

FIG. 12 is an elevational view of a punch utilized for forming the spacing units of FIGS. 5, 6 and 7.

Referring to the drawings, and more particularly to FIGS. 1 and 2, the heat exchanger of the present invention is indicated generally by reference numeral 10 and includes a top tank or supply header 12 and a bottom tank 14 which are interconnected by a core 15 comprising a plurality of water tubes 16 received in a plurality of registering openings 18 in a plurality of stacked fins 20 which are secured to the tubes 16 in heat conductive relation. Coolant flow from the tank 12 to the tank 14 through the tubes 16 in which dissipation of heat occurs with the passage of air across the fins 20. The ns 20 are made from relatively thin metal stock, such as copper or the like, in the order of .0O25.003", and thus are easily deformed.

According to an important feature of the present invention, means are provided for effectively preventing deformation of the fins as the tubes 16 are inserted through the registering openings 18. FIGS. 2, 3, and 4 illustrate one form of the present invention in which each fin 20 is formed with a plurality of spacing units 22. Each of the spacing units 22 is struck from the body of the lin stock and comprises a lug, in the form of a loop 23 having a leg portion 24, a substantially U-shaped portion 26 and an end portion 28 substantially parallel to the leg portion 24. The leg portion 24 and the end portion 28 are substantially perpendicular to the plane of the iin 20. This factor, together with the arcuate configuration of the U-shaped portion 26 provides relatively great compressive strength to the loop and prevents com-pressing of the stack as the tubes are inserted in the tube apertures of the iin stock.

Stamping of the iin stock to form U-shaped spacing unit 22 produces an elongated opening 30. Formed in each of the spacing units 22 simultaneously with each of the loops 23 is a ilow deflector loop 32 which provides both additional secondary heat exchange surface and means to deect the flow of air as it passes across the surface of the fin.

FIG. 10 illustrates a punch for forming the openings 30 and the loops 23 and 32. This punch is indicated by reference numeral 34, is substantially rectangular in cross section, and includes a ledge 36, a surface 38 perpendicular the ledge 36, an angular surface 44 substantially parallel to the surface 38, a shoulder 45, a surface 46 disposed at a relatively great angle with respect to the plane of the ledge 36, and a ledge 48 coplanar with the ledge 36. As the punch 34 pierces the fin stock to form the opening 30, a portion of the metal, corresponding to the area of the top surface 42, is forced outwardly to form the end portion 28. The metal at the left side of this area, as viewed in FIG. 10, is then curled by the surface 40. The n stock at the right side of the area is not punched until the shoulder 45 is reached and the surface 46 protrudes through the stock. Then this material is curled until the punch 34 reaches the position illustrated in FIG. l in which the flow defiector curl 32, having an end section 50 perpendicular to the plane of the same stock, is formed.

Referring more particularly to FIG. 2, it will be noted that the openings 18 are arranged in two transversely spaced, longitudinally offset series in order to provide desirable turbulence- Between each pair of openings 18 there are provided two spacer units 22 oppositely disposed with respect to each other. In the lower series, as illustrated in FIG. 2, the lowermost spacer unit has a spacer curl 23 on the left side and a flow deector curl 32 on the right side. The uppermost of the spacing units 22 has a spacing curl 23 on the right side and a flow deector curl 32 on the left side.

Between each pair of these spacing units is formed a flow deliector unit 51 having curls 52 which are similar to the iiow deflector 32.

The curls 52 are formed by a punch 54 illustrated in FIG. 9. The punch 54 comprises two ledges 56 and 65, two perpendicular surfaces `58 and 64 perpendicular to the ledges and two surfaces 60 and 62 which intersect the surfaces 58 and 64. The apex 61 of the tool is preferably disposed midway between the surfaces 58 and 64,

Both the leading edge 66 and the trailing edge 68 of the iin 20 (FIG. 2) are preferably krinkled or undulated to increase turbulence and impart rigidity to the n section. Each of the openings 18 includes a peripheral flange 70 formed by the punch operation.

In FIG. is illustrated a modified form of the present invention in which the like reference numerals denote like parts. In this form of the invention, however, a plurality of spacer units 76 are disposed between each pair of openings 18. Each of the spacing units 76, as shown clearly in FIG. 5a, includes a pair of adjacent loops 78 each having a leg portion 80, a U-shaped portion 82 and an end portion 84.

The portions 80 and 84 are substantially perpendicular to the plane of the fin stock. i

Each spacer unit 76 is formed by means of a punch illustrated in FIG. l2 and indicated lby reference numeral 86. The punch 86 has a vertical surface 88, as viewed in that figure, a downwardly sloping surface 90, a flat surface 92 perpendicular to the surface 88, a surface 94 sloping upwardly at the same angle as that of surface and a surface 96 parallel to the surface 88. As the punch 86 pierces the n stock, a pair of spaced openings 98 and 100 are formed. The metal is curled as illustrated until the loops 78 are formed. If it is desired to decrease the number of fins per inch, the penetration of the punch 86 may be limited so that the height of the spacer loop 78 above the plane of the fin stock is increased and the spacers assume the position illustrated in dot and dash lines. It will be appreciated that the size of the spacers may be varied a desired merely by the degree of penetration of the punch 86.

FIG. 6 shows another modified form of the invention in which the spacer units 76 are disposed in parallel relation each to the other end and at an angle to the leading edge 66, In this form of the invention, the spacer units 76 are in spaced relation each to the other. In FIG. 7 is illustrated another modied form of the present invention which is similar to that shown in FIG. 6 with the exception that a spacer unit 76 is disposed in contiguous relation to a spacer unit 102 which is similar to the flow deector unit 52 but on a larger scale. As illustrated in that gure, spacer units 76 and 102 are disposed at an angle to the leading edge 66.

FIG. 8 illustrates another modified form of the present invention which includes a plurality of spacer units 104 each of which have a spacer loop similar to loop 23 at one end thereof. The units 104 are oppositely disposed so that the spacing loops are adjacent opposite openings 18 of a pair of openings. The spacer units 104 maybe formed by a punch 108 illustrated in FIG, ll. The punch 108 is similar to the punch 34 of FIG. 10 but has a surface 110 in lieu of the surfaces 42, 44 and 46. By this arrangement curling is effected on only one side.

The method of the present invention includes the steps of providing punches of the type set forth in FIGS. 9, 10, 11 or 12. The present method also includes limiting the depths of penetration of any of the punches illustrated to vary the configuration of the loops and thus control the height of the spacing elements above the plane of the iin stock.

The above described heat exchanger exhibits important advantages over heat exchangers heretofore known. For instance, the formation of the several types of spacer units illustrated provides the rigidity necessary perpendicular to the surface of the n and parallel to the tubes so one fin supports the other and distortion of the fins is minimized when the tubes are inserted. The spacing units are struck from the body of the n stock and thus do not require additional metal, In fact, the ability of this fin to provide an increase in turbulence over previous fins, and the consequent increase in its ability to dissipate heat, permits the use of fewer iins per inch in a core of given dimensions.

Applicant does not intend to be limited by the disclosures of the above described forms of the invention, but rather intends to be limited only by the scope of the appended claims.

What is claimed is:

1. A method for making a heat exchanger comprising the steps of: (l) providing a continuous elongated strip of relatively thin metal; (2) forming a plurality of tube receiving openings in said elongated strip; (3) punching a plurality of integral spacer loops of predeter mined height and a plurality of integral turbulizer loops of substantially less height than said spacer loops from said elongated strip between said tube receiving openings; (4) severing said elongated strip into fins of a predetermined length; (5) stacking a plurality of said fins in superposed relation so that the tube receiving openings thereof are in register each with the other; (6) inserting a plurality of tubes through said openings in heat conductive relation; and (7) joining said ns to said tubes.

2. A method for making a iin for a heat exchanger core of the tube and fin type comprising the steps of: 1) providing an elongated strip of metallic material; (2) punching said strip to form a iirst series of openings adapted to receive tubes, said openings being transversely disposed and longitudinally spaced (3) forming a plurality of spacing units between adjacent tube openings in each series, said spacing units being formed by piercing said strip and curling said pierced portion of said strip until it forms a U-shaped loop having its free end nearly contacting and extending substantially perpendicular to the remaining portion of said strip and; (4) severing said strip into ns of predetermined length.

3. A method for making a fm for a heat exchanger core of the tube and fin type comprising the steps of: (l) providing an elongated strip of metallic material; (2) punching said strip to form a rst series of openings adapted to receive tubes, said openings being transverse disposed and longitudinally spaced; (3) punching said strip to form a second series of openings adapted to receive tubes, said last-named openings being transversely disposed, longitudinally spaced and longitudinally offset with respect to the openings of said first series; (4) piercing said strip to form a plurality of openings and curling the metal from said openings so that there is formed a plurality of spacer loops of predetermined height and a plurality of turbulizer loops of less height than said spacer loops above the level of said strip; and (5) severing said strip into ns of predetermined length.

4. A method for making a fin for a heat exchanger core of the tube and fin type comprising the steps of: (1) providing an elongated strip of metallic material; (2) punching said strip to form a series of openings adapted to receive tubes, said openings being transversely disposed and longitudinally spaced; (3) piercing said strip to form a plurality of openings and curling the metal from said openings to form a plurality of spacer loops having their free ends extending substantially perpendicular to the remaining portion of said strip, each of said spacer loops of predetermined height; (4) piercing said strip to form a plurality of openings and curling the metal from said openings so that there is formed a plurality of turbulizer loops of less height than said spacer loops above the level of said strip and; (5) severing said strip into ns of predetermined length.

References Cited UNITED STATES PATENTS 1,951,958 3/1934 Young 165-182 X 2,048,207 7/ 1936 Krackowizer 29-157.3 X 2,246,258 6/ 1941 Lehman 29-157.3 X 2,428,145 9/1947 Cook. 3,373,803 3/1968 Steinberg et al. 29-157.3 X

FOREIGN PATENTS 958,564 1/ 1957 Germany.

CHARLIE I. MOON, Primary Examiner D C. REILEY, Assistant Examiner 

